The present invention relates generally to a fabric structure, and, more particularly, is directed to a fabric having particular use for vertical blinds.
When forming vertical blinds, for example, as shown and described in U.S. Pat. No. 4,309,472, a single layer of material is generally used. It is generally desirable, when forming such vertical blinds, to use a fabric made of polypropylene or the like, because of the extremely inexpensive nature thereof. However, polypropylene cannot be used in such formation because it degrades when subjected to ultraviolet light and it loses some physical properties--that is, it becomes tender and brittle. Also, a single layer of material may not provide sufficient light-blocking properties.
Fabrics are generally known in which a first type of material is sandwiched between two outer layers of material. Examples of such fabrics are shown and described in U.S. Pat. Nos. 3,025,199; 3,619,336; 3,647,061; 3,649,428; and 4,426,414. These fabrics are adhesively secured together, either by using a separate adhesive or by the adhesive nature of the materials of the different layers.
The three latter U.S. patents have their layers secured together by stitching. However, the sandwiched fabric in these latter U.S. patents is comprised of a cellular sheet material or a batt of self-bonding fibers extending in random directions throughout the batt. With these U.S. patents, the stitching extends in the lengthwise direction thereof.
A problem with all of the above arrangements, as applied to vertical blinds, is that there is a tendency for the elongated slats of the vertical blinds to cup--that is, the slats acquire curvature in the widthwise or transverse direction thereof. It therefore becomes necessary to provide support in such case in the widthwise direction to prevent such cupping action. Additionally, for the same reasons, it is necessary to prevent twisting of the slats in the widthwise direction thereof.
When forming vertical blinds, another problem that arises is that of forming an opaque effect, in which light is prevented from traveling through the slats. At the same time, it is desirable to provide a textural appearance to the slats or blinds and to have both sides thereof with the same appearance.